String. The organization's internal ID (32-character hex string) or its externalSourceId. When the value matches the format of an internal ID, the internal ID takes precedence.

String. The ID of the department to retrieve (32-character hex string), as returned in the id field of the response. Lookup by externalSourceId is not supported for departments, unlike organizationId. The literal value root is reserved: GET .../departments/root always resolves to the organization's root department (see the Get departments root endpoint), so a department whose own id happens to be root cannot be retrieved through this endpoint.